Configure of libdbmusic does checks for libpq++.h and libdb++.so which are not existant on a system with Postgresql 7.3.2 installed. Possible solution: libdbmusic-0.6.1 is available from http://kmusicdb.sourceforge.net/ or change the depends so that Postgresql 7.2.x is required.
You need to have libg++ in USE to get a postgresql with libpq++.
We don't have a way of expressing USE for a dependency. Re-compile postgres with USE=libg++.
Seems to have re-opened itself.